Method of and apparatus for effecting severance of webs in response to changes in transparency along their length

ABSTRACT

In order to automatically cut to size nonuniformly spaced photographs arranged serially to constitute a continuous web, a cutting mechanism to sever the web transversally is operated upon sensing the change in the transparency of the web between a dark margin that frames each photograph and a light strip separating each margin from that of an adjacent photograph. There are provided a first photoelectric sensing station which generates a control signal to stop the web feed and effect cutting when the leading edge of a photograph coincides with the severing path of the cutting mechanism and a second photoelectric sensing station which generates a control signal to stop the web feed and effect cutting when the trailing edge of the same photograph coincides with said severing path.

United States Patent Inventor Werner Schmidt Cologne-Sub, Germany Appl.No. 846,075

Filed July 30, 1969 Patented Aug. 24, 1971 Assignee RbelnischeBraunkohlenworlte AG Cologne, Germany Priority Aug. 2, 1968 Germany P 1761 993.1

1 METHOD OF AND APPARATUS FOR EFFEC SEVERANCE OF WEBS IN RESPONSE TOCHANGE IN TRANSPARENCY ALONG THEIR TING Primary Examiner-James M.Meister Attomey-Edwin E. Greigg ABSTRACT: In order to automatically cutto size nonuniformly spaced photographs arranged serially to constitutea continuous web, a cutting mechanism to sever the web transversally isoperated upon sensing the change in the transparency of the web betweena dark margin that frames each photograph and a light strip separatingeach margin from that LENGTH of an ad acent photograph. There areprovided a first a Cums 2 Drawing Figs photoelectric sensing stationwhich generates a control signal US. Cl. 83/364, to stop the web feedand effect cutting when the leading edge 83/210, 83/365, 83/37 I 250/219PR of a photograph coincides with the severing path of the cutting Int.Cl. 826d 5/34 mechanism and a second photoelectric sensing station whichField ofSearch 83/210, generates a control signal to stop the web feedand effect 209, 364, 365, 371; 250/219 WD,219 LG, 219 cutting when thetrailing edge of the same photograph coin- TH, 219 FR cides with saidsevering path.

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2/ I l8 1 L METHOD OF AND APPARATUS FOR EFFECTING SEVERANCE OF WEBS INRESPONSE TO CHANGES IN TRANSPARENCY ALONG THEIR LENGTH BACKGROUND OF THEINVENTION This invention relates to a method of and apparatus foractuating a cutting deviceto sever a strip or web of indefinite lengthinto portions of predetermined size. The web is of the type whosetransparency regularly and abruptly varies along its length. Such afeature is characteristic, for example, of a web of photographic paperwhich has, along its length, a series of photographs-such astransparencies or the likeof uniform size. Each such photograph isframed by a peripheral dark margin of small transparency and isseparated from one another by a blank (light) strip of greattransparency extending transversally of the web. The spacing of thephotographs from one another is usually nonuniform and thus the lightseparating strips are, accordingly, of differing widths. In order toensure that the transversal cuts correspond to the exact lateral limitsof the photographs themselves, the severing operation has heretoforebeen performed manually. Such manual operation, however, is very timeconsuming and requires an excessive amount of labor.

OBJECT AND SUMMARY OF .THE INVENTION It is an object of the invention toautomatize a cutting operation of the aforenoted type, utilizing theregularly varying transparency of the web along the'length thereof.

Briefly stated, according to the invention, as the web is advanced intoa position in which the severing path of the cutting device coincideswith a line along which the web is to be cut, the change of transparencyof the web is photoelectrically sensed and the generated signal isutilized to control the feed of the web and the cutting operation. Theweb is thus automatically and intermittently advanced; the length ofeach incremental advancement is dependent of the linear intervals atwhich severing cuts are to be effected.

The apparatus for practicing the afore-outlined method is designed insuch a manner that adjacent one web face there is provided a lightsource, while adjacent the opposite web face there is disposed aphotocell cooperating with the light source. The intensity of thelatter, as sensed by the photocell, is controlled by the transparency ofthe interposed, traveling web. The photocell, in turn, controlsflip-flop circuits, the outputs of which correspond to different valuesof light transparency.

The invention will be better understood, as well as further objects andadvantages will become more apparent, from the ensuing detailedspecification of a preferred, although exemplary, embodiment taken inconjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic plan view of onepart of the embodiment, wherein, for the sake of clarity, the web isdisplaced transversally to expose components disposedthereunder; and

FIG. 2 is a circuit diagram of the embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, the web tobe severed is formed of serially arranged individual, successivephotographs 11, ll, 11", etc. spaced from one another by blank strips12, 12, etc. The dimension L of each photograph measured in thedirection of the web travel indicated by arrow 13, is identical, whereasthe dimensions 1, 1' of strips 12, 12', respectively (also taken in thedirection of the web travel), usually differ from one another. Eachphotograph has a dark peripheral margin 14. Thus, the blank (light)strips l2, 12, etc., on the one hand, and the margins 14, on the otherhand, have values of light transparency which substantially differ fromone another.

The web 10 is advanced in the direction of arrow 13 on a table 15 onwhich there is mounted a cutting device schematically shown at C,adapted to sever the web 10 along a linear, transversal cutting path 16.The dimension B of the web 10 measured transversely to the direction 13of the web travel remains unchanged by the severing operations.

In order to obtain a uniform size of LXB as a result of the sequentialcutting operations, each photograph 11,11, 11'', etc. has to be cut outfrom the web 10 by severing along respective leading edges 11a, 11a,11a", etc. and respective trailing edges 11b, 1 lb, etc.

The control of the web feed in the direction of arrow 13 and the controlof the cutting operation is effected by an electronic circuitry(generally indicated at 17 in FIG. 2) which senses the aforenoted lightand dark conditions of the vweb 10 at predetermined locations on table15. For sensing said light" and dark" conditions of the web 10, there isarranged thereabove a number of light sources (not shown) with each ofwhich there is associated a photocell disposed beneath the web 10. Thisembodiment, as shown in FIG. 1, comprises two sensing stations generallyindicated at 18 and 19, respectively, disposed upstream and downstreamof the severing path 16, at a distance L therefrom. The sensing station18 comprises a first group of three photocells 20 and an immediatelyadjacent second group of three photocells 21. Photocells within eachgroup are arranged in a series extending transversally of the directionof web feed, and are thus disposed parallel with the cutting path 16.The two groups of photocells are spaced from the cutting path 16 in sucha manner that when the leading edge 11a of the leading photograph 11coincides with the cutting path 16, as shown in FIG. 1, the photocells20 of the first group are immediately upstream of, and the photocells 21of the second group are immediately downstream of, the trailing edge 11bof the first photograph 11. Stated indifferent terms, the first andsecond groups of photocells of the sensing station 18 are disposed onopposite sides of the trailing edge 11b which forms the borderlinebetween the dark margin 14 of the leading photograph 11 and theimmediately following light strip 12. It is thus seen that in order toensure that the web 10 assumes a correct position for the execution of asevering operation along the leading edge 11a, the photocells 21 have tosense a dark condition and the photocells 20 have to sense a lightcondition.

The provision of a plurality of photocells (each having its ownassociated light source) in each group instead of a single one, isadvantageous in practically eliminating the possibility of generatingfalse signals, since a signal from any of said groups is emitted only ifeach photocell in one group senses a transparency of identical value.

The sensing station 19 disposed at a distance L downstream of thecutting path 16 comprises only a sole light source (not shown) andphotocell 22, which is, in general, sufficient to emit an unambiguoussignal since at this station merely the change from light to dark" hasto be sensed. This event occurs when the leading edge 11a of the leadingphotograph 11 reaches the second sensing station 19- and passes overphotocell 22. In this position of web 10, the dark marginal portion 14disposed immediately upstream of the leading edge 11a, is locatedbetween photocell 22 and its associated light source and the trailingedge 11b of the first photograph 11 coincides with the severing path 16of the cutting device.

In summary, the sensing station 18 serves to determine the position ofthe leading edge of each photograph along the cutting path 16, whereasthe sensing station 19 is actuated when the trailing edge of the samephotograph is in a cutting position.

It is to be noted that the arrangement of sensing stations 18 and 19upstream and downstream of the cutting path 16 is particularlyadvantageous to secure a uniform L B size of cut photographs despitenonuniform spacings 1, 1', etc.

Further, the provision of two adjacent groups of photocells withinsensing station 18 to sense, respectively, a dark and a light fieldseparated by a trailing edge 11b, 11b, etc. is advantageous forparticularly accurately sensing the separating line between thelast-named dark and light fields.

It is to be understood that any other arrangement of the sensingstations with respect to the severing path 16 is feasible within thescope of the invention.

FIG. 2 illustrates the circuitry generally indicated at 17 whichprocesses the signals from photocells 20, 21 and 22 and, accordingly,controls the web feed and the cutting device. Each photocell 20, 21 and22 is connected in series between two voltages, with a matchingpotentiometer 23, 24 and 25, respectively. The output of each photocellsets, through a Schmitt-trigger 26, 27 and 28, respectively, a flip-flopcircuit 29, 30 and 31, respectively. Each flip-flop circuit, as knownper se, is adapted to assume two stable positions (hereinafter calledL"- .and O-positions; with each position there is associated an output(hereinafter called L- and O"-outputs), one of which signals the dark"condition, while the other indicates the light condition.

In case of a light condition, a voltage appears at the L- outputs of theflip-flop circuits 29, and in case of a dark condition, a voltageappears at the O-outputs of the flip-flop circuits 30 and 31. Alloutputs of the flip-flop circuits 29 and 30 are applied to an AND-gate32. To the output side of the latter there is connected the flip-flopcircuit 31 associated with the sensing station 19 and an OR-gate 33.Further, the output of the flip-flop circuit 31 is connected to theinput side of the OR-gate 33.

To the output side of the OR-gate 33 there is connected, on the onehand, through an AND-gate 34 a relay 35 controlling the cutting deviceand, on the other hand, a further flip-flop circuit 36. The O-output ofthe latter is connected with a relay 37 actuating a breaking mechanismschematically indicated at Br preferably of the attracting magnet-type,while the L-output of the flip-flop circuit 36 is connected with a relay38 for controlling the conveying mechanism schematically indicated at CMwhich advances the web 10. Further, across a switch 39, which iscontrolled by the relay 37, the O-output of the flip-flop circuit 36 isconnected to a second input of the AND gate 34.

Further, means may be provided to apply start and stop pulses to theinputs of the flip-flop circuit 36. Also, to a further input of theflip-flop circuit 36 a standby signal may be applied.

OPERATION OF THE EMBODlMENT First, by means of a starting pulse, theflip-flop circuit 31 is readied and the flip-flop circuit 36 is set intoits L-position. Thereby, through relay 38, the conveying mechanism CMfor the web is set into motion. As soon as the web 10 has reached itsposition shown in FIG. 1, the flip-flop circuits 29 connected to theoutput of the photocells are set into their L-position and the flip-flopcircuits 30 connected to the output of the photocells 21 are set intotheir O-position. At the L- and O-outputs, respectively, of the twoaforenoted groups of flip-flop circuits, a voltage appears whichgenerates a voltage at the output of the AND-gate 32. The last-namedvoltage, on the one hand, readies the flip-flop circuit 31 for thesuccessive sensing step in which the leading edge 11a of the photograph11 will cover the photocell 22, and, on the other hand, generates avoltage at the output of the OR-gate 33. This lastnamed voltage, on theone hand, readies the AND-gate 34 and, on the other hand, sets theflip-flop circuit 36 into its O- position. Thereby, the relay 37,associated with the braking mechanism Br, is energized and through relay38 the conveying mechanism CM for the web 10 is deenergized. The relay37 closes the switch 39 so that a second voltage is applied to the inputside of the AND-gate 34. By virtue of the latter occurrence, the relay35 is energized and thus actuates the cutting mechanism C which seversthe web 10 along the leading edge 11a of the photograph 11. Uponcompletion of the cutting operation, a standby signal, which may betriggered by the cutting mechanism, resets the flip-flop circuit 36 intoits L- position whereby the relay 38 is again energized and thus theconveying mechanism CM restarted to again advance the web 10. Thisconveying operation ends when the leading edge 11a, precedingly severedalong line 16, reaches the sensing station 19 and there passes beyondthe photocell 22. At that moment, the photocell 22 senses dark and theflip-flop circuit 31 is set into its O-position and another cuttingoperation is effected by a sequence as described hereinbefore. At thistime, the trailing edge 11b of the photograph 11 coincides with thecutting line 16, so that during the aforenoted second cutting operation,the web 10 is severed transversally along trailing edge 11b. As a resultof the two cutting operations, the photograph 11 is, in exact LXB size,separated from the web 10.

The subsequent conveying operation ends at the moment when the trailingedge 11b of the second photograph 11' reaches the sensing station 18 andis disposed between the two groups of photocells 20 and 21. Thereafter,the abovedescribed cycle is repeated for cutting out the second photograph 11' and then the third photograph 11", etc. It is thus seen thatthe web 10 of indefinite length is cut alternately, on the one hand,into portions of identical size LXB corresponding to the individualphotographs and, on the other hand, into waste strips of the size IXB,l'XB, etc.

That which I claim is:

1. An apparatus for actuating a cutting mechanism to effect, along acutting path, a transversal severance of a web of indefinite lengthadvanced in the longitudinal direction thereof, said web including alongits length alternately repetitive adjacent fields of two types havingtwo substantially differing values of transparency, the border linebetween two adjoining fields of said two types extending transversallyof the length dimension of said web, said apparatus comprising,

A. at least one sensing station including at least one first photocelland at least one second photocell; said first and said second photocellsbeing disposed adjacent one face of said web and juxtaposed with respectto one another in the longitudinal direction of said web; said first andsecond photocells being spaced from said cutting path to such an extentin said longitudinal direction as to be located at different sides ofsaid border line when the desiredline of severance on said web coincideswith said cutting path, and

B. electronic circuit means adapted to receive transparency-responsivesignals from said sensing station and to actuate said cutting mechanismwhen a change of transparency is sensed, said electronic circuit meansincluding a flip-flop circuit associated with each sensing station, eachflip-flop circuit adapted to receive said signals and deliver twooutputs corresponding to said two substantially differing values oftransparency.

2. An apparatus as defined in claim 1, wherein a plurality of said firstphotocells forms a first group of photocells arranged in a juxtaposedseries extending parallel to said cutting path and a plurality of saidsecond photocells forms a second group of photocells arranged in ajuxtaposed series extending parallel and immediately adjacent to theseries of photocells of said first group, said first and second groupsare located at different sides of said border line when the desired lineof severance on said web coincides with said cutting path of saidcutting mechanism.

3. An apparatus as defined in claim 1, wherein fields of one type haveidentical predetermined lengths in the longitudinal direction of saidweb, including A. a first sensing station disposed upstream of saidcutting path at a distance therefrom corresponding to said predeterminedlength to sense a change from the transparency of one type of field tothe transparency of the other type of field when a desired first line ofseverance on said web coincides with said cutting path, and

B. a second sensing station disposed downstream of said cutting path ata distance therefrom corresponding to said predetermined length to sensethe passage of the leading edge of said web when a desired second lineof severance on said web coincides with said cutting path; said leadingedge is formed by a'cut coinciding with said first line of severance;the distance between the first and second lines of severance isidentical to said predetermined length.

4 An apparatus as defined in claim 1, including an AND- gate to whichthe output of each of said flip-flop circuits is applied, the outputvoltage of said AND-gate is adapted to effect the interruption of theweb feed and the actuation of said cutting mechanism.

5. An apparatus as defined in claim 3, including an AND- gate to whichthe output of at least one flip-flop circuit associated with saidfirstsensing station is applied, the output of said AND-gate is coupledwith the input of the flip-flop circuit associated with said secondsensing station; the output of said AND-gate is also coupled with aninput of an OR-gate, another input of the latter is connected to anoutput of the last-named flip-flop circuit; the output of said OR-gateis adapted to effect the interruption of the web feed and the actuationof said cutting mechanism.

6. An apparatus as defined in claim 5, wherein the output of saidOR-gate is applied to an additional flip-flop circuit, one output'ofwhich is connected with a control means of a braking mechanism, theother output of which is connected with a control means associated witha conveying mechanism for the web feed.

7. An apparatus as defined in claim 6, wherein the output of saidOR-gate is also applied to an additional AND-gate, the output of whichis connected with a control means associated with said cuttingmechanism. I

8. An apparatus as defined in claim 7, wherein an input of saidadditional AND-gate is connected through a circuit breaker switch tothat output of said additional flip-flop circuit which is connected tothe control means of said braking mechanism; said circuit breaker switchis adapted to be closed by the last-named control means uponenergization thereof by said additional flip-flop circuit.

1. An apparatus for actuating a cutting mechanism to effect, along acutting path, a transversal severance of a web of indefinite lengthadvanced in the longitudinal direction thereof, said web including alongits length alternately repetitive adjacent fields of two types havingtwo substantially differing values of transparency, the border linebetween two adjoining fields of said two types extending transversallyof the length dimension of said web, said apparatus comprising, A. atleast one sensing station including at least one first photocell and atleast one second photocell; said first and said second photocells beingdisposed adjacent one face of said web and juxtaposed with respect toone another in the longitudinal direction of said web; said first andsecond photocells being spaced from said cutting path to such an extentin said longitudinal direction as to be located at different sides ofsaid border line when the desired line of severance on said webcoincides with said cutting path, and B. electronic circuit meansadapted to receive transparencyresponsive signals from said sensingstation and to actuate said cutting mechanism when a change oftransparency is sensed, said electronic circuit means including aflip-flop circuit associated with each sensing station, each flip-flopcircuit adapted to receive said signals and deliver two outputscorresponding to said two substantially differing values oftransparency.
 2. An apparatus as defined in claim 1, wherein a pluralityof said first photocells forms a first group of photocells arranged in ajuxtaposed series extending parallel to said cutting path and aplurality of said second photocells forms a second group of photocellsarranged in a juxtaposed series extending parallel and immediatelyadjacent to the series of photocells of said first group, said first andsecond groups are located at different sides of said border line whenthe desired line of severance on said web coincides with said cuttingpath of said cutting mechanism.
 3. An apparatus as defined in claim 1,wherein fields of one type have identical predetermined lengths in thelongitudinal direction of said web, including A. a first sensing stationdisposed upstream of said cutting path at a distance therefromcorresponding to said predetermined length to sense a change from thetransparency of one type of field to the transparency of the other typeof field when a desired first line of severance on said web coincideswith said cutting path, and B. a second sensing station disposeddownstream of said cutting path at a distance therefrom corresponding tosaid predetermined length to sense the passage of the leading edge ofsaid web when a desired second line of severance on said web coincideswith said cutting path; said leading edge is formed by a cut coincidingwith said first line of severance; the distance between the first andsecond lines of severance is identical to said predetermined length. 4.An apparatus as defined in claim 1, including an AND-gate to which theoutput of each of said flip-flop circuits is applied, the output voltageof said AND-gate is adapted to effect the interruption of the web feedand the actuation of said cutting mechanism.
 5. An apparatus as definedin claim 3, including an AND-gate to which the output of at least oneflip-flop circuit associated with said first sensing station is applied,the output of said AND-gate is coupled with the input of the flip-flopcircuit associated with said second sensing station; the output of saidAND-gate is also coupled with an input of an OR-gate, another input ofthe latter is connected to an output of the last-named flip-flopcircuit; the output of said OR-gate is adapted to effect theinterruption of the web feed and the actuation of said cuttingmechanism.
 6. An apparatus as defined in claim 5, wherein the output ofsaid OR-gate is applied to an additional flip-flop circuit, one outputof which is connected with a control means of a braking mechanism, theother output of which is connected with a control means associated witha conveying mechanism for the web feed.
 7. An apparatus as defined inclaim 6, wherein the output of said OR-gate is also applied to anadditional AND-gate, the output of which is connected with a controlmeans associated with said cutting mechanism.
 8. An apparatus as definedin claim 7, wherein an input of said additional AND-gate is connectedthrough a circuit breaker switch to that output of said additionalflip-flop circuit which is connected to the control means of saidbraking mechanism; said circuit breaker switch is adapted to be closedby the last-named control means upon energization thereof by saidadditional flip-flop circuit.